Hidrológiai Közlöny 1948 (28. évfolyam)
ÉRTEKEZÉSEK - JAKUCS LÁSZLÓ: A hévforrásos barlangkeletkezés földtani és fizikai tényezői
ÍO HIDROLÓGIAI KÖZLÖNY XXVIII. év f. 1.9/,8. 1—4. ír: rim. ship evidently proves that Karst Water is mostly fed that is, they are at right angle to its contour lines. by precipitation. The new Karst Water contour map shows that the altitude of the Karst Water table depends on three factors: precipitation, distance of the erosion basis and topography. It has to be pointed out that the contour map fixes mean values of the variable, oscillating water level. Therefore some differences from the given altitudes are possible. Notwithstanding, the contour map gives information of the direction of flow in the moving zone of the water table, as it is evident that the main directions of flow are parallel to the slope of the water table, Besides its scientific importance the Karst Water Map has practical value: 1. from a hygienic point of view,» because the map shows below what depth an abundant, constant and adequate drinking water supply may be expected, 2. for industry planning, because it gives information on possibilities of industrial water supply, 3. for coal mining, because it indicates possibilities of efficient mine development in areas threatened by Karst Water and increases the safety of mine operations. Every future effort for Karst Water or against it can avail itself of this map. »4 RÉSUMÉS FRANCAIS - BRIEF SUMMARIES KURZE AUSZUGE RIASSUNTI ITALIANI Mining Old Tertiary Coals, Karst Water and Prevention of its Dangers in Hungary. By F. Kassai. (Hungarian text with figs, and tables on p. 4.) J>. ('. 6Í2.33:551.444<43».11 > The chief source of energy in Hungary is brown coal, especially Old Tertiary coal. Our output of brown coal is 3.45% of that of the world (Tables I, II and III.), 60% of our brown coal resources are represented by coals above 3800 kilocalories and 50% of our output are produced from Old-Tertiary coal fields. (Fig. 1 and 2. Tables IV—VII.) The greatest problem of mining Old Tertiary coals is the reduction of the danger of Karst water inbreaks. This paper therefore deals in detail with the origin and with the phenomena of Karst Water and with methods of fighting irruptions of such water. Karst water mainly originates from precipitations soaking through the surface. Its average level in Transdanubian Hungary, where the mining of Old Tertiary coals is most important, may be characterized by an approximate contour map (Fig. 3.) on basis of hitherto available observations (Table VIII. 1. Oscillation of the Karst Water Table is mainly caused by the variation of precipitations and of the erosion basis. Of relationships deduced the almost identical variation of the Karst Water level and of precipitations has to be pointed out. Precipitations in Transdanubian Hungary (Fig. 4.) generally follow orography, (There is much more precipitation in the interior of the Central Mountains than on their borders.) and therefore along isohietes surrounding the mountains, the Karst water level is fairly constant. Karst water level is highest where precipitations have been strongest. Rise and fall of the Karst Water Table follow precipitation with a lag of 2—3 months. (Fig. 5.) To prove this relationships a map is drawn across Pusztaszentlászló, Keszthely, Veszprém and Esztergom. (Fig. 6.). Another influence upon the configuration of the Karst Water Table is that of tapping. Tapping is effected at the erosion basis. Such are in Transdanubian Hungary: Lake Balaton, the eastern promontories of the Bakony Mountains in the County of Fejér, the Danube (Fig. 11.) and the Tata Valley. Tapping at the erosion basis produces a parabolic water surface. (Fig. 7, 8, 9.) Farther from the tapping place the curve assumes the shape of a double parabola composed of a convex and a concave portion which meet in a point of inflection. It is probable that the effect of immediate 4 From a hygienic point of view it will be important to denote on the map zones of hidden Karst. Considering these areas and directions of flow areas supplying healthy drinking water can be delimitated. A further task will be to find out if anywhere greater areas of depressed Karst Water level can be found in the Transdanubian country. tapping reaches to the inflection point, and farther from this the water table assumes a natural position depending on meteorologic and topographic conditions. Parabolas corresponding to different erosion bases are similar to one another, a mean parabola can be designed from them on basis of which the effect of the erosion basis on the Karst Water Table can be determined at any place. (Fig. 10.) Of Karst Water phenomena the effect of the Danube on the Tokod Karst Water Table may still be pointed out. (Fig. 11.) Connections between occurrenccs of Karst Water at 10 Km distance from one another and between several cave systems may still be referred to. Karst Water threatens mining by irruptions into the workings, dangerous water level may oscillate between rather wide limits, (Table IX.) and development operations in endangered areas demand serious consideration. Occasional inbreaks of water prove the connection of the cave systems. Examinations showed that Darcy's formula holds good not only for water flowing in sands but also along cavities and cave systems. Prevention of danger due to Karst Water is effected by filling up the Karstic cavities, by drainage and by leaving back protection pillars. The filling method requires the execution of previous geophysical researches to locate the position and strike of the Karstic cavities and to determine the location of boreholes of sufficient feed capacity. The feed capacity of a drill hole can vary between very wide limits and can be increased by acidizing witli hydrochlorich acid. Researches have proved that in directions showing' major feed capacity the degree of Karstification is greater. The capacity of feed of drill holes can be illustrated by data on cementing executed in the Dorog mining district. (Table X, Fig. 12 and 13.) here feed data generally show a similar process. In directions at right angles to each other ratios of quantities of water absorbed vary from 1.2 — 2. Similar relationships are found between the permeability factors of the two directions to water. This prooves again that Darcy's formula holds for Karst water moving through underground channels. Drill holes of adequate feed capacity are injected with sand-cement or loess-cement slurry. (Table XI.) Numerous tests were made to find out the proper mixture: the segregation of the components of the mixture, settling speed, and the permeability to water
